This invention relates to thermosetting resin compounds excelling in heat resistance, electric insulation, mechanical strength and workability,
Known thermosetting resins include epoxy resin, phenolic resin, silicone resin and polyester resin. However, none of these conventional thermosetting resins are satisfactory in respect of high temperature characteristics. For instance, it is known that epoxy resin declines in mechanical strength at higher temperature from 100.degree. C. and is deteriorated at a temperature of about 180.degree. C. to fall in electric insulation. In contrast, resins based on maleimide such as polyaminobismaleimide is known to have a prominent heat resistance. However, resins of maleimide series have the drawbacks that bismaleimides have a high melting point, are little soluble in an ordinary organic solvent with the resultant low workability, and require high temperature and long hours for hardening.